Is it within Famitracker to simulate the effect of the una pedal? For clarification, the left-most pedal on piano, which changes the timbre of the note, making it kinda ethereal. What effects would I use? I have all channels available for this in a (private, for now) VRC6 module. I just want to know if it can be done, or maybe some tips on emulating it.

Assuming that your piano instrument is a duty cycled V02 to V06 instrument, you could simulate the soft pedal by making an instrument with the same volume envelope but a different, less plucky duty envelope. The sustain pedal could be done with echo effects or by alternating channels every note.